PROCESS FOR PREPARING N-(2,6-DICHLORO-3-METHYLPHENYL)-5-7-DIHALO[1,2,4]TRIAZOLO[1,5A]PYRIMIDINE-2-SULFONAMIDE BY CYCLIZATION AND HALO-DEHYDROXYLATION

Abstract: The invention relates to a process for making DCSA by cyclization of DCM-ATSA with an acid and phosphorus pentachloride to produce DHSA and two isomeric compounds known as HCSA. The resulting compounds from the cyclization are halo-dehydroxylated to produce DCSA.

Description: PROCESS FOR PREPARING N-2, 6-DICHLORO-3-METHYLPHENYL) -5-7-DIHALO[1, 2,4]TRIAZOLO [l,5A]PYRIMIDINE-2-SULFONAMIDE BY CYCLIZATION AND HALO-DEHYDROXYLAT ON Field of the Invention The invention relates to a process for preparing an intermediate which could be used for the production of an agricultural product, such as a herbicide, fungicide or insecticide. More specifically, the invention relates to an improved process for making N- (2, 6-dichloro-3-methylphenyl) , (4- bromo-2,6 dichloro-3-methylphenyl) , (2, 6-dibromo-3- methylphenyl) , (2, 4-dibromo-3-methylphenyl) , (4, 6-dibromo-3- methylphenyl) , or (4-bromo-3-methylphenyl) , -5-7- dihalo[l, 2, 4] triazolo [1, 5a]pyrimidine-2-sulfonamide (which are all hereinafter referred to as DCSA) . Background of the Invention DCSA is an agricultural intermediate used to produce agricultural herbicides, pesticides and the like. Typically, DCSA is made by cyclizing an amino triazole with dimethyImalonate and sodium methoxide to form a 5,7-dihydroxy pyrimidine intermediate. The pyrimidine intermediate is isolated by filtration, aqueous washing and drying, but these steps lead to partial decomposition of the pyrimidine ring. The pyrimidine intermediate is further converted to DCSA with phosphorus oxychloride. The problem with this method is that the yields in both reactions are very low, the method is unreliable and has two aqueous to anhydrous solvent changes. An additional problem with this method is that the DCSA is isolated by distillation of the phosphorus oxychloride to a tar residue that is followed by an aqueous work-up and filtration. .Another method of making DCSA is to treat an amino triazole with malonyl chloride in acetonitrile to form 5,7 dihydroxy pyrimidine intermediate and to dry it. The residues are then dissolved in phosphorus oxychloride and heated to 90°C for greater than 24 hours. .Another technique is to treat an aminotriazole with an acid, such as malonic, in phosphorus oxychloride and heat the mixture to 90°C for greater than 24 hours. In both reactions, after the unreacted phosphorus oxychloride is evacuated, the resulting mixture contains tars and is quenched with water to isolate the 5,7 dihalo pyrimidine. This method is preferred to the previous method discussed above, but is still disadvantageous because malonic acid decomposes under high temperatures, high phosphorus waste streams are created, and the resulting desired compounds are of low purity. Therefore it is highly desirable to have a process that does not create phosphorus waste streams, uses catalysts and solvents that are easy and economical to handle from a manufacturing, environmental and cost perspective and that results in high yields of the desired products. -2- SUBS UTE SHEET (RULE 26) Summary of the Invention The invention relates to a process for making DCSA by cyclizing DCM-ATSA with an acid and phosphorus pentachloride in the presence of a solvent to produce two isomeric compounds known as HCSA and DHSA . The resulting intermediates from the cyclization are converted by a halo-dehydroxylation reaction to produce DCSA. Prior to cyclization reaction of DCM-ATSA, phosphorus pentachloride is made in-situ. Phosphorus pentachloride is made by reacting phosphorus trichloride and chlorine gas. The solvent in the reaction is typically phosphorus oxychloride. The reaction is exothermic, but the temperature of the reaction is usually maintained between about -20°C and about 80°C. After the phosphorus pentachloride is formed, the reactor is charged with DCM-ATSA and an acid. The DCM-ATSA and acid additions are exothermic, so the temperature is controlled between about 0°C to about 60°C. It is thought that DCM-ATSA and phosphorus pentachloride react to form a DCM-ATSA-PCI4 adduct which further reacts with the acid. After the acid is added to the reactor, the DCM-ASTA-PCI4 intermediate is cyclized with the acid under cool conditions to produce DHSA and HCSA intermediates. The conversion of DHSA and HCSA to DCSA by the halo-dehydroxylation reaction with phosphorus oxychloride is accelerated by increasing the temperature of the reactor. A co-product of the halo-dehydroxylation reaction is dichlorophosphoric acid. The phosphorus oxychloride solvent is regenerated from the dichlorophophoric acid by treatment with phosphorus pentachloride. Complete recovery of the phosphporus oxychloride may be achieved typically by distillation. The resulting DCSA product may be isolated using standard distillation and filtration techniques. Several other acids may be cyclized with the DCM-ATSA to make a substituted triazolo pyrimidine. These acids could include malonic acid, substituted malonic acid, and beta- ketocarboxylic acid or substituted carboxylic acid. However to make the DHSA or HCSA, malonic acid is used. The above described process has several advantages over other processes, which include increased yields, nearly complete elimination of phosphorus waste and complete recovery of the phosphorus oxychloride solvent. .Another advantage is that, in a preferred embodiment of the invention, solid phosphorus pentachloride is not used, but is generated in solution with phosphorus trichloride and chlorine gas. Solid phosphorus pentachloride rapidly decomposes in air and tends to agglomerate such that it is difficult to handle. Solid phosphorus pentachloride is also very corrosive. Therefore, it is highly desirable to develop a process where solid phosphorus pentachloride need not be used. • 4- SUBSTΠUTESHEET(RULE26) Brief Description of the Drawings Figure 1 is a reaction schematic of one of the preferred embodiments of the invention, where the acid employed in the cyclization is malonic and the solvent is phosphorus oxychloride. Detailed Description of the Invention The invention relates to an improved process for making N- (2, 6-dichloro-3-methylphenyl) , (4-bromo-2,6 dichloro-3- methylphenyl) , (2, 6-dibromo-3-methylphenyl) , (2, 4-dibromo-3- methylphenyl), (4, 6-dibromo-3-methylphenyl) , or (4-bromo-3- methylphenyl) , -5-7-dihalo[1, 2,4] triazolo [1, 5a]pyrimidine-2- sulfonamide (which all are hereinafter referred to as DCSA) by cool cyclization of N- (2, 6-dichloro-3-methylphenyl) , (4-bromo- 2,6 dichloro-3-methylphenyl) , (2, 6-dibromo-3-methylphenyl) , (2, 4-dibromo-3-methylphenyl) , (4, 6-dibromo-3-methylphenyl) , or (4-bromo-3-methylphenyl) , -5-amino[1,2,4] triazole-3-sulfonamide (which are all hereinafter referred to as DCM-ATSA) with an acid and phosphorus pentachloride to produce N- (2, 6-dichloro-3- methylphenyl) , (4-bromo-2,6 dichloro-3-methylphenyl) , (2,6- dibromo-3-methylphenyl) , (2 , 4-dibromo-3-methylphenyl) , (4,6- dibromo-3-methylphenyl) , or (4-bromo-3-methylphenyl) , -5,7- dihydroxy[1,2,4]triazolo[1, 5a]pyrimidine-2-sulfonamide (which are all hereinafter referred to as DHSA) and two isomeric compounds which are N- (2, 6-dichloro-3-methylphenyl) , (4-bromo- -5- SUBST1TUTESHEET(RULE26) 2,6 dichloro-3-methylphenyl) , (2, 6-dibromo-3-methylphenyl) , (2, 4-dibromo-3-methylphenyl) , (4, 6-dibromo-3-methylphenyl) , or (4-bromo-3-methylphenyl) , -5-hydroxy-7- chloro[1,2, 4]triazolo [1,5a]pyrimidine-2-sulfonamide and N-(2,6- dichloro-3-methylphenyl) , (4-bromo-2,6 dichloro-3-methylphenyl) , (2, 6-dibromo-3-methylphenyl) , (2, 4-dibromo-3-methylphenyl) , (4, 6-dibromo-3-methylphenyl) , or (4-bromo-3-methylphenyl) , -5- chloro-7-hydroxy[1,2,4]triazolo[1, 5a]pyrimidine-2-sulfonamide (which are all hereinafter after referred to as HCSA) . The resulting intermediates from the cyclization are then converted to DCSA by halodehydroxylation. To make DBΞA, which would be structurally the same as DCSA except that the pyrimidine portion of the molecule would be substituted with bromine instead of chlorine, the conditions and process for making DCSA are followed; however the liquid bromide, phosphorus bromide, phosphorus pentabromide and phosphorus oxybromide are used. Typically the process would comprise cyclizing DBM-ATSA with an acid selected from the group consisting of malonic and substituted malonic acid in the presence of phosphorus pentabromide and a phosphorus oxybromide at a temperature between O'C to 60"C to produce DHSA and DBSA intermediates. After cyclization is complete, the intermediates are bromo-dehydroxylated to form a DBSA product. Prior to cyclization of DCM-ATSA, phosphorus pentachloride is made in-situ. Phosphorus pentachloride is made by reacting -6- SUBSDTUTE SHEET (RULE 26) phosphorus trichloride and chlorine gas. If desired, phosphorus pentachloride may be purchased instead of being made in-situ and is available from Twin Lakes Chemical in Lockport, New York. It is preferred to form the phosphorus pentachloride prior to adding the other reactants. To form phosphorus pentachloride, between about 0.1 to about 5 mole-equivalents of chlorine gas, where hereinafter one mole is equivalent to one mole of DCM-ATSA, is added slowly to between about 0.1 to about 5 mole-equivalents of phosphorus trichloride. Preferably, between about 1.5 to about 2.5 mole-equivalents of chlorine gas is reacted with between about 1.5 to about 2.5 mole-equivalents of phosphorus trichloride, most preferably 2.2 mole-equivalents of phosphorus trichloride is used. The reaction between chlorine gas and phosphorus trichloride is exothermic, so the reaction temperature is typically maintained between about -20°C to about 80°C, preferably between about 0° to about 50°C. The temperature is controlled by a heat sink or by adjusting the chlorine addition rate. To control the temperature within the ranges described herein, typically chlorine is added in an amount between about 1.5 to about 2.5 mole-equivalents in about 2 to about 4 hours. Preferably, prior to charging the chlorine gas through the reactor, a solvent is added to the reactor. The solvent may be phosphorus oxybromide, or phosphorus oxychloride. Other co- solvents may be used if so desired and could include -7- SUBST1TUTE SHEET (RULE 26) chlorotoluene, methylbenzoate, methyl pivalate, chlorobenzene or alkyl benzenes, or acetonitrile. If phosphorus oxychloride is the solvent, it is used in an amount between about 4 mole- equivalents to about 100 mole equivalents. Typically about 10 mole-equivalents of phosphorus oxychloride is used. When co- solvents are employed, the phosphorus oxychloride is typically used in an amount of 2 or greater mole-equivalents. If a co- solvent is used, the phosphorus oxychloride may be added any time prior to the halo-dehydroxylation reaction. Upon forming the phosphorus pentachloride, the temperature of the mixture is preferably adjusted to between about 0°C to about 60°C, more preferably between about 0°C to about 20°C. Typically, the temperature is less than 10"C. After the acid is added to the reactor, the reactor is adjusted to a temperature between about 10°C to about 100°C, preferably betweeen about 10°C to about 30°C. The most preferred temperature is about 20°C After the phosphorus pentachloride is formed, the reactor is charged with DCM-ATSA and an acid. One mole equivalent of DCM-ATSA is added. All reagents are based on one mole equivalent of DCM-ATSA. Typically, between about 0.5 to about 5 mole-equivalent of the acid is added. Preferably, between about 0.8 to about 1.2 mole-equivalents per one mole of DCM-ATSA is used. The acid is selected from the group consisting of malonic acid, substituted malonic acid, where the substitution is methyl or phenyl, beta-ketocarboxylic acid, and substituted carboxylic acid. The substituted carboxylic acid is selected from the group consisting of cyanoacetic acid, aceto acetic acid, methyl malonic acid, malonic nitrile acid and phenyl malonic acid or salts thereof. Preferably, lithum, sodium or potassium salts are used. It is thought that DCM-ATSA reacts with the phosphorus pentachloride to produce a DCM-ATΞA-PCI4 adduct and hydrochloric acid, and that the phosphorus pentachloride also reacts with the acid to produce an acid intermediate and hydrochloric acid. It is further thought that the DCM-ATSA-PCI4 adduct is cyclized with the acid intermediate. Preferably, although not essential, DCM-ATSA is added to the reactor prior to the addition of the acid intermediate. Because the additions are exothermic, the temperature may be controlled by adjusting the rate that the DCM-ATSA and acid are added to the reactor. The temperature in the reactor during the addition is typically maintained between about 0° to about 60°C, preferably between about 0° to about 20°C, most preferably the temperature is maintained below 10°C. The cooler temperatures assist in minimizing acid decomposition and in keeping the hydrochloric acid in solution. After the acid is added to the reactor, the reactor is adjusted to a temperature between about 10°C to about 100°C, typically between about 10°C to about 50°C, preferably between about 10°C to 30°C. Most preferred the temperature is about 20°C. The DCM-ATSA-PCI4 -9- SUBST17UTESHEET RULE26 intermediate is cyclized with the acid intermediate to produce DHSA and HCSA. Typically, cyclization is complete between about 4 to about 40 hours, preferably between about 12 to about 24 hours at 20°C. The ratio of the resulting intermediates is dependent upon the temperature of the cyclization, the concentration of the reactants and the amount of hydrochloric acid present in the mixture. Typically the ratio of intermediates is between about 3:1 to about 1:3 DHSA to HCSA. After cyclization, halo- dehydroxylation is accelerated by increasing the temperature of the reactor. The temperature is increased to between about 30°C to about 105°C, preferably between about 75°C to about 95°C to increase the rate of halo-dehydroxylation. It should be noted that during the cool cyclization it is thought that there might be a small amount of halo-dehydroxylation occurring. When the temperature is increased, the rate of the halo-dehydroxylation increases. A co-product of the halo-dehydroxylation reaction is dichlorophosphoric acid or HOPOC12- Dihalophosphoric acid is a co-product that represents a potentially large phosphorus waste and it is thought to affect the halo-dehydroxylation rate. As the dihalophosphoric acid concentration increases, the reaction rate appears to decrease. It is thought that the phosphorus pentachloride may function as a reactant to halogenate the dihalophosphoric acid and convert the dihalophosphoric acid back -10- SUBST1TUTE SHEET (RULE 26) to phosphorus oxychloride. The conversion may be completed by the second in-situ formation of phosphorus pentachloride either during or after the halo-dehydroxylation reaction. It is preferred to add between greater than 0 to about 2.5 mole equivalents of phosphorus pentachloride. The phosphorus pentachloride may be added after the temperature is increased to accelerate the halo-dehydroxylation reaction. The phosphorus pentachloride is preferably made in-situ as discussed previously and is made once the halo-dehydroxylation temperature reaches about 80°C. By adding the phosphorus pentachloride during the halo- dehydroxylation reaction, it is thought that the conversion time of intermediates HCSA and DHSA to DCSA is decreased from about between about 45 hours to about 20 hours. The halo- dehydroxylation conversion rate of DHSA and HCSA to DCSA may also be increased by the addition of ςhloride ion catalysts. These catalysts may be selected from the group consisting of lithum chloride, sodium chloride, potassium chloride, calcium chloride, tetraalkylammonium chloride, such as tetramethylammonium chloride, pyridinium-hydrochloride and the like. Conversion of DHSA and HCSA to DCSA usually takes between about 20 to about 60 hours, but typically between about 35 to about 50 hours. Generally, the conversion of the intermediates to the final product is greater than 95 percent. The recovery of the solvent may be initiated either during or after the halo-dehydroxylation reaction. More preferably, the solvent is recovered under partial vacuum. The solvent may be distilled off and recycled as the initial loading for the next cycle of reactions. A flux solvent that has a boiling point higher than the boiling point of phosphorus oxychloride, that is non-reactive with the DCSA product may be used. The flux solvent does not have to be miscible with phosphorus oxychloride. The flux solvent is selected from the group consisting of halobenzene, alkylbenzene and substituted benzene. Preferably the flux solvent is alkylbenzene. Other flux solvents that could be used and may be selected from xylene, dichlorobenzene, chlorobenzene, nitrobenzene, chlorotoluene, anisole and the like. Most preferably, the flux solvent is xylene. The flux solvent is used to recover the remaining solvent that was not removed in the initial distillation. Typically between about 5 to about 25 equivalents of the solvent are recovered. Another distillation method may also be completed for total recovery of the solvent. After halo-dehydroxylation and recovery of the solvent, the reaction solution is cooled to a temperature between about 10°C to about 70°C, preferably between about 20°C to about 50°C. A recovery solvent such as methanol, ethanol, propanol or butanol may be added to the reaction solution, which contains the flux solvent and DCSA. Any recovery solvent may be used provided -12- SUBSTmJTE SHEET (RULE 26) that the solvent improves the solubility of the side products and lowers the solubility of the DCSA so that the DCSA may be separated from the reaction solution by filtration. It should be noted that the phosphorus oxychloride may also be recovered after the point of filtration of the DCSA product. After filtering out the DCSA, xylene could be added to the residual mixture and then the phosphorus oxychloride could be distilled off. Preferably, the flux solvent used in the recovery of the solvent is xylene and the recovery solvent used to help disolve unwanted side products out of the resulting DCSA product is methanol. It is thought that the combination of xylene and methanol lowers the DCSA solubility, yet dissolves any impurities that may be present in the reaction mixture. After the recovery solvent is added, typically the reaction solution is maintained at a temperature between about 0°C to about 70°C for between greater than 0 to about 100 hours, preferably the reaction solution is maintained at a temperature between about 20°C to about 50°C for greater than 0 to about 2 hours. The resulting slurry is filtered to isolate the DCSA. Figure 1 is an illustration of one of the preferred embodiments of the invention. The phosphorus pentachloride is made in-situ and the DCM-ATSA and malonic acid are added to a reactor along with phosphorus oxychloride. After the cyclization is complete, the resulting intermediates, DHSA and -13- S BST1TUTESHEET RULE26 HCSA, undergo a chloro-dehydroxylation reaction to produce the final product DCSA. The co-product dichlorophosphoric acid may be converted back to the solvent phosphorus oxychloride with phosphorus pentachloride. Examples The following examples outline general procedures and operating conditions which may be used to produce DCSA. The examples are presented to illustrate the invention and should not be construed as limiting the scope of the invention. Example 1 Example 1 consists of three operations: reactions, distillation, and DCSA isolation. The scale of the process was 0.8 mole of DCM-ATSA, and one mole-equivalent, therefore, equals 0.8 mole. Part A- Reaction Cyclization and Halo-dehvdroxylation A 2-liter reactor was purged with nitrogen and charged with POCI3, 10 mole-equivalents/mole of DCM-ATSA and PCI3,. and 2.2 mole-equivalents/mole DCM-ATSA. The reactor was equipped with an air-driven, overhead stirrer and thermowell. The kettle top had a total of five necks. A -14- SUBSTTTUTESHEET(RULE26) circulating bath fed and controlled the temperature of the DOWTHERM LF™ in the jacket of this reactor. The reactor was vented through a dry-ice condenser, a 1 liter knock-out flask and a 1 liter caustic trap. A mineral oil bubbler was placed after the knock-out flask to prevent water vapor from reaching the reactor. Both POCI3 (10 mole equivalents) and PCI3 (2.2 mole equivalents) are liquids that were added to the reactor at 20°C. Through a 0.5-inch teflon addition tube, chlorine gas (2.2 mole- equivalents/mole of DCM-ATSA) was slowly added over approximately 1.5 hours. The reaction of chlorine gas with PCI3 was exothermic. The temperature of the contents were kept below about 30°C. Because the product of this reaction, PCI5, was a solid and not very soluble in POCI3 at this temperature, the mixture became a slurry. Slight nitrogen pressure was sometimes kept with the CI2 to prevent plugging in the addition tube. A dry-ice condenser was used to minimize chlorine loss. After the chlorine charge, the addition tube was removed, and a stopper was put in its place. The reactor contents were then cooled to about 6°C. The reactor was charged with two solids: 1 mole-equivalent of DCM-ATSA and 1.02 mole-equivalents of malonic acid. Because these additions were exothermic, the rates were adjusted to keep the slurry temperature below 10°C. This cold addition kept HCl in solution and minimized malonic acid decomposition. The reactor contents were then warmed to about 20 °C. After 13 to 16 hours at this temperature, the cyclization of the DCM-ATSA/PCI4 adduct was considered complete. After the cyclization of DCM- ATSA/PCI4 adduct, the rate of the chloro-dehydroxylation of DHSA and HCSA with POCI3 was increased by raising the reactor temperature to 80°C. Sufficient conversion to DCSA required about 40 hours at this temperature. The slurry was cooled to approximately 25°C before the reactor was charged with PCl3,and 4 mole equivalents/mole of DCM-ATSA. Through the same 0.5-inch teflon addition tube, 2.1 mole-equivalents of chlorine were again added slowly (over approximately 1.5 hours) to the reactor. The PCI5 reacted with the dichlorophosphoric acid to produce POCI3. The temperature of the slurry was kept below 80°C. After the chlorine charge, the addition tube was removed, and a stopper was put in its place. Part B- Distillation The equipment was then prepared for vacuum distillation to recover the POCI3. The dry-ice condenser was replaced with a distillation column on the kettle top. This vacuum-jacketed and silvered column had a 1-inch internal diameter and a 32-inch packing height. The packing was 1/8 inch glass helices. A second circulation bath was used to feed the DOWTHERM LF™ to the condenser at -16- SUBSTITIJTE SHEET (RULE 26) 6°C. An acetone/dry-ice bath was also used to cool the overhead receiving flask to reduce the vapor pressure of the collected liquid. Vacuum was achieved with a belt- driven, single-stage pump. The system pressure was controlled with a vacuum regulator and measured with a mercury manometer. The pump, manometer and regulator were protected by two dry-ice traps. An absolute pressure of about 250 mmHg was achieved. This reduced pressure allowed the distillation to run at lower temperatures which minimized DCSA decomposition. The jacket temperature was then raised to 100°C to begin the distillation. The temperature drop from the jacket to the reactor contents was normally about 20°C during the distillation. The reflux ratio was controlled with a timer, electromagnetic coil and magnetic distilling head. The first overhead cut was collected with a constant reflux ratio of 2. This overhead cut consisted of approximately 2 mole-equivalents of PCI3 and 10 mole-equivalents of POCI3. This material was stored in a tightly-capped bottle for recycle to the next batch run as the initial solvent charged in the beginning of the reaction. To facilitate the recovery of the remaining solvent, the reflux ratio was increased to 6. The jacket temperature and absolute pressure were 100°C and approximately 250 mmHg, respectively. The temperature drop -17- SUBST1TUTESHEET(RULE26) from the jacket to the reactor contents was about 20°C. This second overhead cut was about 4 mole-equivalents of POCI3, which was the amount generated from PCI5 during the cyclization of DCM-ATSA and conversion of dichlorophosphoric acid. A mixture of 4 mole-equivalents of POCI3 and 1.5 mole-equivalents of o-xylene was charged to the reactor during the collection of this second distillate through the addition funnel. A nitrogen blanket was kept above the liquid addition funnel. This feed allowed the recovered POCI3 to be of high purity. The feed was normally charged continuously over three of the five hours needed for collection. The recovered POCI3 was stored in a separate, tightly capped bottle. The third overhead cut had a composition approximately equal to the material fed during the collection of the second overhead cut described above. This final distillate, therefore, was intended for recycle to the next batch run distillation. The absolute pressure, reflux ratio and jacket temperature were 80 mmHg, 5, and 100°C, respectively, during the collection. The temperature drop from the jacket to the reactor contents was normally about 20°C. The reactor was charged continuously with 7 mole- equivalents of o-xylene over four of the six hours needed for collection. This distillate was stored in a separate, tightly capped bottle. -18- SUBSTTTUTE SHEET (RULE 26) Part C- DCSA Isolation After the distillation, the reactor contained a slurry of o-xylene, DCSA, some side products, and traces of phosphorus oxychloride. The distillation column was removed from the reactor to prevent contamination. When the reactor contents were at ambient pressure and 50°C, 7 to 21 mole-equivalents of methanol were added to help dissolve the side products. The slurry was then kept at 50°C for approximately one hour. The reactor contents were cooled to 25°C, drained, and filtered. The resulting solid was washed with 2 to 3 cake volumes of methanol. The density of the wet cake was about 1.0 g/mL. The mother-liquor/filtrate mixture was stored in a tightly capped bottle. A piece of latex was then placed over the cake and vacuum maintained to remove excess solvent. Example 2 The procedures described in Example 1 were followed, except that the reaction conditions for trials 1 through 15 varied according to the conditions specified in Table 1 and the DCSA was isolated prior to the phosphorus oxychloride recovery. -19- TABLE 1 Trial Cyclization Chlorination Equiv. of DCSA Isolated Purity of No. Temp C Temp POCI3 Grams Material 1 30 85 10 68.97 94.8 2 40 92 14 64.8 95.1 3 20 92 14 64.5 95.36 4 40 78 6 65.44 94.4 5 20 92 6 76.7 82.4 6 30 85 10 70.1 91.4 7 40 78 14 64.66 96.3 8 40 92 6 65.25 94 9 20 78 6 70.45 93.92 10 20 78 14 69.8 96.8 11 30 85 10 65.35 93.3 12 30 85 10 62.8 95 13 20 78 14 69.74 96.7 14 15 74 17 68.87 95.81 15 15 74 17 69.62 96.17 -Repeat Assay 85 10 70.1 90 TABLE 1 Continued Trial Active DCSA Filtrate Yield Lost to DCSA Total No. Y% Grams (Y%) Filtrate Yield % 1 78.93 8.47 10.22 89.15 2 74.39 8.71 10.51 84.90 3 74.25 10.3 12.43 86.68 4 74.57 8.78 10.60 85.17 5 76.29 6.27 7.57 83.86 6 77.34 7.07 8.53 85.88 7 75.17 9.69 11.70 86.86 8 74.04 6.93 8.37 82.41 9 79.87 5.29 6.39 86.26 10 81.56 8.29 10.01 91.57 11 73.60 8.47 10.22 83.83 12 72.02 11.03 13.31 85.33 13 81.41 7.52 9.08 90.49 ■ 14 79.65 7.57 9.14 88.79 15 80.82 7.07 8.53 89.36 -Repeat 75.7 84.35 As can be seen from Table 1, the range of DCSA conversion was between about 82 to about 91 percent with an isolated active yield range of between about 72 to about 82 percent.

Claims: We Claim: 1. A process for making DCSA comprising cyclizing DCM-ATSA with malonic acid in the presence of phosphorus pentachloride and a phosphorus oxychloride solvent at a temperature between about O'C to about 60 "C to produce a mixture of DHSA and DCSA intermediates, wherein after cyclization is complete, the intermediates mixture is chloro-dehydroxylated to form a DCSA. 2. The process of Claim 1, wherein prior to cyclization phosphorus pentachloride is made from reacting chlorine gas with phosphorus trichloride. 3. The process of Claim 1, wherein the amount of phosphorus pentachloride is between about 2 to about 2.5 mole equivalents per mole of DCM-ATSA. 4. The process of Claim 1, wherein between about 0.5 to about 5 mole equivalents of acid is used per one mole of DCM-ATSA. 5. The .process of Claim 4, wherein, between about 0.8 to about 1.2 mole equivalents of acid is used with one mole of DCM-ATSA. 6. The process of Claim 1, wherein the temperature of the reaction between DCM-ATSA and acid is maintained between about 10 * C to about 100 "C. 7. The process of Claim 6, wherein the temperature is between about 10'C to about 30"C 8. The process of Claim 7, wherein the temperature is about 20 * C. 5 9. The process of Claim 1 wherein the temperature is increased between about 30'C to about 105'C to accelerate chloro- dehydroxylation 10. The process of Claim 9, wherein the temperature during halo-dehydroxylation is between about 75 * C to about 95'C. 10 11. The process of Claim 1, wherein dichloro-phosphoric acid is a coproduct of the chloro-dehydroxylation. 12. The process of Claim 11, wherein phosphorus pentachloride react with the dichloro-phosphoric acid to make phosphorus oxychloride. 15. 13. The process of Claim 12, wherein between greater than 0 to about 2.5 mole equivalents of phosphorus pentachloride is added to during the chloro-dehydroxylation. 14. The process of Claim 1, wherein the solvent is recovered by distillation and a flux solvent is added during distillation, 20 where the resulting reaction mixture recovered contains DCSA and a flux solvent. 15. The process of Claim 14, wherein the flux solvent is halobenzyene, alkylbenzene or substituted benzene. 16. The process of Claim 15, wherein the flux solvent is xylene, dichlorobenzene, nitrobenzene, chlorotoluene or anisole. 17. The process of Claim 15, wherein a recovery solvent is added after distillation to the resulting mixture and the recovery solvent is methanol, ethanol, propanol or butanol. 18. The process of Claim 1, wherein the rate of conversion of DHSA and HCSA to DCSA is increased by the addition of chloride ion catalysts. 19. The process of Claim 18, wherein the chloride ion catalyst is selected from the group consisting of lithum chloride, sodium chloride, potassium chloride, calcium chloride, tetraalkylammonium chloride, and pyridinium-hydrochloride. 20. The process of Claim 19, wherein the tetraalkylammonium chloride is tetramethylammonium chloride. 21. The process of Claim 1, wherein a co-solvent is used with the phosphorous oxychloride and is selected from the group consisting of chlorotoluene, methylbenzoate, methyl pivalate, chlorobenzene, alkyl benzene, and acetonitrile. 22. A process for making DBSA comprising cyclizing DBM-ATSA with an acid selected from the group consisting of malonic and substituted malonic acid in the presence of phosphorus pentabromide and a phosphorus oxybromide at a temperature between 0 * C to 60 * C to produce DHSA and DBSA intermediates, wherein after cyclization is complete, the intermediates are bromo-dehydroxylated to form a DBSA.

Inventors: BUDD JEFFREY T, RINGER JAMES W, TOBEY RICHARD E, ZETTLER MARK W, BUDD, JEFFREY, T., RINGER, JAMES, W., TOBEY, RICHARD, E., ZETTLER, MARK, W.
Applicants: DOWELANCO
Application year: 1994
Main classification: C07D487
IPC codes: A61K31, A61P31, C07D487